The present invention relates to methods of improving the adherence and/or centering of intra-corneal implants to the corneal bed. More particularly, the invention relates to methods for pre-treating intra-corneal implants so that the implants, after being placed in contact with the cornea, effectively self-center and adhere to the corneal bed, for example, without sutures.
Various treatments are known for correcting corneal refractive errors. The use of lasers, for instance, to reshape the cornea by removing corneal tissue, has become increasingly popular in recent years. However, the removal of tissue can result in loss of the structural integrity of the cornea, and can also cause bulging.
Furthermore, once corneal tissue has been removed, it can not easily be restored. Thus, laser vision correction is substantially irreversible.
The need for a reversible treatment which does not adversely affect the structural integrity of the cornea has led to the use of intra-corneal implants, which do not require the removal of tissue. Instead, a single small incision is made in the cornea to make a flap or hinge, which is then folded back to expose the middle layer of corneal tissue known as the stromal bed. A corrective lens, typically formed of hydrogel material, is placed on the stromal layer. Then the flap is returned to its initial position and smoothed over the lens.
Various techniques have been used for affixing the lens to the cornea once it has been embedded. In some cases, sutures are used. Other techniques eliminate sutures, but rely on a very close match between the curvature of the lens and the curvature of the recipient""s eye. None of these techniques have been entirely satisfactory, resulting in some slippage between the lens and the cornea, and improper positioning in the eye.
Therefore, it would be advantageous to develop methods and apparatus for enhancing the adherence and/or centering of intra-corneal implants on the corneal bed.
New apparatus and methods for treating intra-corneal implants to enhance centering and adherence have been discovered. The present invention addresses one or more of the concerns of the prior art systems, such as those noted above. Moreover, the present methods are straightforward, relatively easy to produce, use and practice, and provide substantial benefits to both the surgeon implanting the intra-corneal implants, and the patient receiving the implants.
In one broad aspect of the invention, a partially hydrated lens is provided for implantation into the stroma of a cornea. The partially hydrated lens comprises an amount of fluid selected to create an osmotic pressure gradient with respect to fluids in the cornea. This osmotic pressure gradient enhances adhesion of the lens to the cornea. In addition, the lens is configured to expand and flatten as it absorbs water from the cornea, naturally centering itself prior to flattening.
In another broad aspect of the invention, the partially hydrated lens is packaged in a hypertonic hydrating solution.
In still another broad aspect of the invention, a method of treating refractive errors in a cornea comprises implanting a partially hydrated lens formed of a hydrophilic polymeric material lens into the cornea, wherein the osmotic pressure differential between the partially hydrated implant and the cornea causes the implant to adhere to the cornea. In one embodiment, the step of implanting the partially hydrated lens is preceded by a step of wetting a pre-hydrated lens with a hypertonic aqueous hydration medium. In another embodiment, the step of implanting the partially hydrated lens is preceded by a step of drying a more hydrated lens.
Each and every feature described herein, and each and every combination of two or more of such features, is included within the scope of the present invention provided that the features included in such a combination are not mutually inconsistent.
These and other broad aspects and advantages are set forth in the following detailed description and claims, particularly when considered in conjunction with the accompanying drawings in which like parts bear like reference numerals.